The invention relates to a piecing device that can travel along an open end spinning machine or the like, with means for receiving a yarn end of a broken yarn from a spool of a spinning assembly, means for guiding the yarn end back to a yarn take-off passage and to a spinning rotor of the spinning assembly, means to take off the pieced yarn and wind it onto the spool of the spinning assembly, and means for transferring the running yarn to a take-off device and to a winding device of the spinning assembly. By way of background information, and as an aid to understanding the present invention, reference is hereby made to co-pending U.S. application Ser. No. 493,158, filed July 30, 1974; co-pending U.S. application Ser. No. 655,853, filed Feb. 6, 1976; U.S. Pat. No. 3,924,393; and U.S. Pat. No. 3,924,394; which applications and patents relate to and disclose apparatus and methods for piecing threads in open-end spinning machines.
In a known device (German OS 2,505,943) there is the problem that in transfer of the pieced yarn to the spinning assembly devices, the yarn deflection via the piecing device has to be reversed. In the known construction there is attention to management of the transfer of the running yarn so that it is effected as rapidly as possible, so that the drop in yarn tension associated therewith will not have too pronounced an effect on the zone of the spinning turbine, where it could lead to a break in the yarn. It has been found in practice that with piecing devices of this kind quite good piecing can be produced, but there are other irregularities in the produced yarn, particularly, thick places at a relatively long distance away from the piecing.
The invention is addressed to the problem of developing arrangements whereby the produced yarn will present no more thick places after piecing, but rather will have a uniform appearance. This problem is solved according to an important provision of the invention in that the means for taking off and winding the pieced yarn and the means for transferring the running yarn after the piecing are controlled so as to be adapted to the course of the transfer motion, whereby a uniform denier will be obtained, corresponding to the denier produced by the spinning assembly.
The invention starts from the finding that the thick places occurring at a distance from the piecing device are caused by the relatively great differences or changes in the yarn take-off rate in transferring the yarn from the piecing device to the spinning assembly in question. These differences are prevented by the invention. Directly after the piecing device, both during the guiding of the yarn into the piecing device and also during the transfer of the yarn to the spinning assembly, the same denier is produced that is spun by the spinning assembly. The invention rests on the principle that compensation of fluctuation will not work because fluctuations will already have caused changes in yarn quality. It is therefore provided that the yarn be transferred to the spinning assembly under meticulously controlled conditions, whereby the rate of yarn take-off--at least as calculated on the quantity of supplied sliver--will be kept constant, without fluctuation or disturbance.
These and other objects, features and advantages of the present invention will become more apparent from the following description when taken in connection with the accompanying drawings, which show, for purposes of illustration only, several embodiments in accordance with the present invention.